If the raw data does not come from a normal population the mean itself may still follow a normal distribution.
Therefore in your case use a t-distribution as the population standard deviation is not known.
Determine whether the hypothesis test involves a sampling distribution of means that is a normal distribution, student t distribution, or neither.
Claim ,u=78
sample data
n=24
x=101
s=15.3
The sample data, for this simple random sample, appear to come from a population with a distribution that is very far away from the normal, and o~ is unknown.
If the raw data does not come from a normal population the mean itself may still follow a normal distribution.
Therefore in your case use a t-distribution as the population standard deviation is not known.